In recent decades, significant attention has been called to the issue of motor vehicle safety. According to various studies, motor vehicle accidents rank among the top causes of accidental injury or death. On highways, for example, where vehicles are traveling at high speeds, a sudden visibility loss due to rain, dense fog, snow, or forest fire, may result in a multi-vehicle pileup costing significant property damage, injuries, and even death.
Motor vehicle manufacturers have responded to the safety concerns by developing driver assistance systems such as Adaptive Cruise Control (ACC), Forward Collision Warning (FCW) system, Blind Spot Warning System (BSWS), and Lane Departure Warning (LDW) system. Generally, these systems monitor the vehicle environment by taking measurements of objects using radar, laser and/or camera-based sensors to assist the driver.
For example, an ACC system helps drivers maintain a preset distance from the vehicle they are following using a radar module mounted at the front of the vehicle that measures the gap and closing speed to the vehicle ahead. The ACC system may automatically adjust the speed of the car to help maintain a preset distance from the vehicle in front. Similarly, FCW uses a combination of radars, lasers and/or cameras to activate a visual and audible warning when the system detects a high risk of collision with the vehicle in front. BSWS uses side and rear-looking radars and cameras to detect other vehicles around the vehicle, and illuminates an indicator lamp in the side-view mirrors when an object is present in the driver's blind spot. Finally, an LDW system uses small, forward facing camera to monitor lane lines and alerts the driver when an unintentional lane departure is happening.
Accordingly, each of the above-identified systems relies on radars, lasers, cameras, and/or other sensors mounted locally on the vehicle itself. However, if one or more sensors become blocked by snow, ice or mud, each of these systems would be unable to warn the driver or prevent a collision. Furthermore, during adverse weather conditions (e.g., snow, ice or rain), the roads may not provide sufficient traction. Thus, given the short effective range of the conventional systems, even if one of the sensors mounted on the vehicle detects an imminent collision and automatically applies the vehicle brakes, the vehicle may not be able to stop in time to prevent a collision.